JP3961541B2 - Radio base station antenna and radio communication system - Google Patents

Description

  The present invention relates to a radio base station antenna using a leaky transmission path and a radio communication system using the radio base station antenna.

Conventionally, as a wireless system using a leaky transmission line such as a leaky coaxial cable as a radio base station antenna, for example, a leaky coaxial cable dedicated to transmission and a leaky coaxial cable dedicated to reception with higher radiation efficiency are arranged in parallel. A device in which this is connected to a wireless base station device is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 7-15378

  The one described in this patent document uses a leaky coaxial cable dedicated to reception with high radiation efficiency, so that the sensitivity as a reception antenna is increased, and weakness from a wireless terminal device with lower transmission power than a wireless base station device. The effect of being able to efficiently convert high-frequency radio waves into high-frequency power is achieved.

However, due to the principle characteristic of a leaky coaxial cable that the transmission loss per unit length increases as radiation efficiency increases, the received power is reduced to a radio base station apparatus when the leaky coaxial cable is as long as several hundred meters. A large loss occurs in the process of cable transmission to the receiving unit, and there is a problem that reliable reception cannot be performed. For this reason, in order to perform bidirectional communication, the length of the leaky coaxial cable dedicated to reception must be limited to a short length. As a result, the length of the radio base station antenna must be shortened, and the radio communication range is limited. There was a problem of narrowing.
The present invention provides a radio base station antenna and a radio communication system that can sufficiently lengthen the length of a leaky transmission path, thereby ensuring a sufficient radio communication distance.

  The present invention relates to a leaky transmission line that transmits transmission power from the transmission input end toward the terminator and transmits received power in the direction of the transmission input end, and a low loss transmission line that has a smaller transmission loss per unit length than the leaky transmission line. And a first direction that is disposed near the transmission input end of the leaky transmission path and has a function of passing transmission power from the transmission input end toward the terminator and a function of outputting reception power toward the transmission input end to the outside. And has a function of passing transmission power from the transmission input end toward the termination unit and a function of detouring the reception power toward the transmission input end to the low loss transmission line. The second directional coupler is arranged corresponding to the first directional coupler, and the received power output from the first directional coupler and the received power from the low-loss transmission line are input and combined. Output power to the receiving output In the wireless base station antenna with a power combiner for.

  According to the present invention, it is possible to provide a radio base station antenna and a radio communication system in which the length of the leaky transmission path can be sufficiently increased, thereby ensuring a sufficient radio communication distance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
This embodiment describes a radio base station antenna.

  In FIG. 1, 1 is a leaky transmission line that transmits transmission power from the transmission input terminal IN to the terminator 2 and transmits received power from the outside in the direction of the transmission input terminal IN, that is, in the opposite direction. For example, a leaky coaxial cable.

  In the vicinity of the transmission input end of the leaky coaxial cable 1, there is a function of passing transmission power from the transmission input end IN toward the terminator 2 and a function of outputting reception power toward the transmission input end IN to the outside. One directional coupler 3 is arranged.

  In the middle of the leaky coaxial cable 1, a low loss coaxial cable 4 which is a low loss transmission line has a function of passing transmission power from the transmission input end IN toward the terminator 2 and a reception power toward the transmission input end IN. The second directional coupler 5 having a function of making a detour output is disposed. The low-loss coaxial cable 4 is a cable having a transmission loss per unit length smaller than that of the leaky coaxial cable 1.

  Corresponding to the first directional coupler 3, the received power output from the first directional coupler 3 is input via the coaxial cable 6 of a very short distance and from the low-loss coaxial cable 4. Is received, and a power combiner 7 is provided for outputting the combined power to the reception output terminal OUT. Note that the received power output from the first directional coupler 3 may be directly input to the power combiner 7 without using the coaxial cable 6.

  In the radio base station antenna having such a configuration, the transmission power input to the transmission input terminal IN transmits the leaky coaxial cable 1 in the direction of the terminator 2 as shown by the solid line arrow in the figure, and gradually in the middle. Radiated to the outside. Thereby, wireless communication with a wireless terminal device installed outside becomes possible. The power radiated from the outside is received by the leaky coaxial cable 1, and the received power is transmitted as indicated by the dotted arrow in the figure.

The received power received in the section 1 a between the first directional coupler 3 and the second directional coupler 5 is transmitted from the leaky coaxial cable 1 to the power combiner 7 via the first directional coupler 3. Entered. The received power received in the section 1b between the second directional coupler 5 and the terminator 2 is transmitted from the leaky coaxial cable 1 to the low loss coaxial cable 4 via the second directional coupler 5. Further, it is input to the power combiner 7.
The power combiner 7 combines the received power from the first directional coupler 3 and the received power from the low-loss coaxial cable 4 and outputs the combined power to the reception output terminal OUT.

  As described above, the received power received by the section 1a of the leaky coaxial cable 1 through wireless communication with the wireless terminal device is input from the first directional coupler 3 to the power combiner 7. At this time, since the distance from the reception output terminal OUT is short, sufficient reception power is output from the reception output terminal OUT.

  The received power received by the section 1 b of the leaky coaxial cable 1 by wireless communication with the wireless terminal device is input from the second directional coupler 5 to the power combiner 7 via the low-loss coaxial cable 4. At this time, although the distance from the reception output terminal OUT is long, the reception power is transmitted through the low-loss coaxial cable 4, so that sufficient reception power is output from the reception output terminal OUT.

  Therefore, even when the length of the leaky coaxial cable 1 is increased, the wireless communication in the section 1b of the leaky coaxial cable 1 is achieved by appropriately arranging the second directional coupler 5 and the length of the low-loss coaxial cable 4. The reception power from the terminal device can be transmitted without being greatly attenuated, and sufficient reception power can be obtained from the reception output terminal OUT. As a result, a sufficient wireless communication distance can be secured, and thus a wide wireless communication range can be secured.

(Second Embodiment)
This embodiment also describes a radio base station antenna.

  In FIG. 2, 11 is a leaky transmission line that transmits transmission power from the transmission input terminal IN to the terminator 12 and transmits received power from the outside in the direction of the transmission input terminal IN, that is, in the opposite direction. For example, a leaky coaxial cable.

  In the vicinity of the transmission input end of the leaky coaxial cable 11, there is a function of passing transmission power from the transmission input end IN toward the terminator 12 and a function of outputting reception power toward the transmission input end IN to the outside. One directional coupler 13 is arranged.

  A function of passing transmission power from the transmission input end IN toward the terminator 12 to the end of the leaky coaxial cable 11 closest to the terminator 12 and reception power directed toward the transmission input end IN from the low-loss coaxial cable 14 A second directional coupler 15 having a function of making a detour output is disposed. The low-loss coaxial cable 14 is a cable having a transmission loss per unit length smaller than that of the leaky coaxial cable 11.

  A function of transmitting transmission power from the transmission input terminal IN toward the terminator 12 between the first directional coupler 13 and the second directional coupler 15 in the leaky coaxial cable 11 and the transmission input terminal A third directional coupler 16 that outputs received power directed in the IN direction to the outside from the leaky coaxial cable 11 is disposed.

  Corresponding to the first directional coupler 13, the received power output from the first directional coupler 13 is input via the coaxial cable 17 of a very short distance and from the low-loss coaxial cable 14. The first power combiner 18 is arranged to input the received power and output the combined power to the reception output terminal OUT. Note that the received power output from the first directional coupler 13 may be directly input to the first power combiner 18 without using the coaxial cable 17.

  Corresponding to the third directional coupler 16 in the middle of the low-loss coaxial cable 14, the received power output from the third directional coupler 16 is input via the coaxial cable 20 of a very short distance. And a second power combiner 21 that receives the received power from the low-loss coaxial cable 14 and supplies the combined power to the first power combiner 18 via the low-loss coaxial cable 14. ing. Note that the received power output from the third directional coupler 16 may be directly input to the second power combiner 21 without using the coaxial cable 20.

  In the radio base station antenna having such a configuration, the transmission power input to the transmission input terminal IN is transmitted through the leaky coaxial cable 11 toward the terminator 12 as shown by the solid line arrow in the figure, and gradually in the middle. Radiated to the outside. Thereby, wireless communication with a wireless terminal device installed outside becomes possible. The power radiated from the outside is received by the leaky coaxial cable 11, and the received power is transmitted as indicated by the dotted arrow in the figure.

  The received power received in the section 11a between the first directional coupler 13 and the third directional coupler 16 is a first power combination from the leaky coaxial cable 11 via the first directional coupler 13. Is input to the device 18. Also, the received power received in the section 11b between the third directional coupler 16 and the second directional coupler 15 is transmitted from the leaky coaxial cable 11 via the third directional coupler 16 to the second directional coupler 16. Input to the power combiner 21. The received power received in the section 11 c between the second directional coupler 15 and the terminator 12 is transmitted from the leaky coaxial cable 11 to the low-loss coaxial cable 14 via the second directional coupler 15. , And input to the second power combiner 21.

  The second power combiner 21 combines the received power from the third directional coupler 16 and the received power from the low-loss coaxial cable 14 and sends the combined power to the low-loss coaxial cable 14a on the reception output end side. Output. The first power combiner 18 combines the received power from the first directional coupler 13 and the received power from the low-loss coaxial cable 14a, and outputs the combined power to the reception output terminal OUT.

  Thus, the received power received by the section 11a of the leaky coaxial cable 11 by wireless communication with the wireless terminal device is input from the first directional coupler 13 to the first power combiner 18. At this time, since the distance from the reception output terminal OUT is short, sufficient reception power is output from the reception output terminal OUT.

  Also, the received power received by the section 11b of the leaky coaxial cable 11 by wireless communication with the wireless terminal device is transmitted from the third directional coupler 16 through the second power combiner 21 and the low loss coaxial cable 14a. 1 to the power combiner 18. At this time, although the distance from the reception output terminal OUT is long, the reception power is transmitted through the low-loss coaxial cable 14, so that sufficient reception power is output from the reception output terminal OUT.

  Also, the received power received by the section 11c of the leaky coaxial cable 11 by wireless communication with the wireless terminal device is the low loss coaxial cable 14, the second power combiner 21, the low loss coaxial from the second directional coupler 15. It is input to the first power combiner 18 via the cable 14a. At this time, although the distance from the reception output terminal OUT is further increased, the reception power is transmitted through the entire length of the low-loss coaxial cable 14, so that sufficient reception power is output from the reception output terminal OUT.

  Therefore, the length of the leaky coaxial cable 11 can be further increased. And even if it lengthens, the radio | wireless which communicates by radio | wireless in the area 11c of the leaky coaxial cable 11 by making arrangement | positioning of the 2nd, 3rd directional couplers 15 and 16 and the length of the low loss coaxial cable 14 appropriate. The reception power from the terminal device can be transmitted without being greatly attenuated, and sufficient reception power can be obtained from the reception output terminal OUT. As a result, the wireless communication distance can be more sufficiently secured, and therefore the wireless communication range can be further secured.

  In this embodiment, the case where the number of the third directional couplers 16 arranged between the first directional coupler 13 and the second directional coupler 15 is one is described. The present invention is not necessarily limited to this, and two or more may be arranged with a predetermined interval. In this case, of course, the second power combiner increases in accordance with the increased third directional coupler.

(Third embodiment)
This embodiment describes a radio communication system using a radio base station antenna. The radio base station antenna in this embodiment has the same configuration as that of the first embodiment described above.

  In FIG. 3, reference numeral 31 denotes a radio base station apparatus, which connects the transmission input terminal IN of the radio base station antenna 30 via a coaxial cable 32 to the transmission antenna terminal 31a, and is coaxial to the reception antenna terminal 31b. A reception output terminal OUT of the radio base station antenna 30 is connected via a cable 33.

The radio base station antenna 30 includes a leaky coaxial cable 1, a terminator 2, a first directional coupler 3, a low-loss coaxial cable 4, a second directional coupler 5, a coaxial cable 6 and a power combiner 7. It is configured.
A wireless terminal device 34 is disposed around the section 1a of the leaky coaxial cable 1, and a wireless terminal device 35 is disposed around the section 1b.

  In this radio communication system, the radio base station apparatus 31 outputs transmission power to the transmission input terminal IN of the radio base station antenna 30 via the coaxial cable 32 when performing radio communication with the radio terminal apparatuses 34 and 35. This transmission power passes through the first directional coupler 3 and the second directional coupler 5 and is transmitted through the leaky coaxial cable 1. Then, in the section 1a, the radiated radio wave is received by the wireless terminal device 34. In addition, the radio wave is received by the wireless terminal device 35 in the section 1b.

  Transmission power from the wireless terminal device 34 is received in the section 1 a of the leaky coaxial cable 1. The received power at this time is supplied from the section 1 a to the power combiner 7 via the first directional coupler 3 and the coaxial cable 6. And it is input from the power combiner 7 to the reception antenna terminal 31 b of the radio base station apparatus 31 via the reception output terminal OUT and the coaxial cable 33. In this way, the radio base station apparatus 31 and the radio terminal apparatus 34 can perform radio communication using the radio base station antenna 30.

  Further, transmission power from the wireless terminal device 35 is received in the section 1 b of the leaky coaxial cable 1. The received power at this time is supplied from the section 1 b to the power combiner 7 via the second directional coupler 5 and the low-loss coaxial cable 4. And it is input from the power combiner 7 to the reception antenna terminal 31 b of the radio base station apparatus 31 via the reception output terminal OUT and the coaxial cable 33. Thus, the radio base station device 31 and the radio terminal device 35 can perform radio communication using the radio base station antenna 30.

  Since the radio base station antenna 30 can sufficiently increase the length of the leaky coaxial cable 1, the radio base station device 31 can sufficiently secure a radio communication distance with the radio terminal device. Therefore, the radio base station apparatus 31 can communicate with a radio terminal apparatus located far away via the leaky coaxial cable 1. Moreover, since the length of the leaky coaxial cable 1 can be made sufficiently long, it is not necessary to arrange many radio base stations as in the case where the length of the leaky coaxial cable is short.

By the way, in this wireless communication system, the transmission loss of the leaky coaxial cable 1 in the section 1a is α1 (dB), and the transmission of the low-loss coaxial cable 4 from the detour output point of the second directional coupler 5 to the power combiner 7 is performed. When the loss is α2 (dB), the transmission power of the radio base station apparatus 31 is P1 (dBm), and the transmission power of the radio terminal apparatus is P2 (dBm),
α1−α2 ≧ P1−P2 (1)
When the relationship is satisfied, the power reaching the radio base station device 31 from the radio terminal device is equal to or higher than the power reaching the radio terminal device from the radio base station device 31.

  In the above equation (1), when both transmission powers P1 and P2 are fixed, α1 is the transmission loss per length or unit length of the leaky coaxial cable 1, and α2 is the length or unit length of the low loss coaxial cable 4. This relational expression can be satisfied by determining the transmission loss.

  In actual sites such as tunnels and underpasses, in many cases, the range in which wireless communication is desired is determined in advance, and the length of the leaky coaxial cable to be laid is inevitably determined accordingly. In such a case, the transmission loss may be determined so as to satisfy the above equation (1).

  For example, the total length L of the leaky coaxial cable 1 to be laid is 200 m, of which the sections 1a and 1b are each 100 m, the length of the low-loss coaxial cable 4 parallel to the section 1a is 100 m, and the transmission power P1 of the radio base station apparatus 31 20 dBm, the transmission power P2 of the wireless terminal device is 10 dBm, the minimum reception sensitivity of the wireless base station device 31 and the wireless terminal device is −80 dBm, and the maximum distance from the leaky coaxial cable 1 to the wireless terminal device in the vertical direction is 1.5 m. And

  Also, a standard dipole antenna transmitted from the radio base station apparatus 31 and transmitted through the leaky coaxial cable 1 to reach an arbitrary point in the leaky coaxial cable 1 and a point 1.5 m away from the point in the vertical direction. Is defined as a coupling loss, and its value is 65 dB.

  A part of the transmission power output from the radio base station apparatus 31 is consumed due to resistance loss in the process of being transmitted through the leaky coaxial cable 1 and becomes a loss. Another part of the electric power is radiated as a radio wave from each slot on the leaky coaxial cable 1 and is lost. Accordingly, the transmission loss α1 when passing through the leaky coaxial cable 1 is the total value of these losses per meter.

For example, when the wireless terminal device is located at a point 1.5 m vertically away from the front end portion (near the terminator) of the leaky coaxial cable 1, the transmission power Pr1 from the wireless base station device 31 required to reach the wireless terminal device Is
Pr1 = P1− (200 × α1 + 65)
It is represented by The conditions under which this wireless terminal device normally receives are as follows:
Pr1 ≧ −80 dBm
Because
α1 ≦ 0.175dB
It becomes.

On the other hand, it is transmitted from the wireless terminal device, is received by a slot near the tip after 1.5 m spatial propagation, is transmitted through the section 1b of the leaky coaxial cable 1, and is low-loss coaxial via the second directional coupler 5. The power input to the cable 4 is
P2− (65 + 100 × α1)
Therefore, the transmission power Pr2 of the wireless terminal device that reaches the wireless base station device 31 through the 100 m low-loss coaxial cable 4 is
Pr2 = P2− (65 + 100 × α1) −100 × α2
It is represented by Since the condition for the radio base station apparatus 31 to normally receive is Pr2 ≧ −80 dBm, α2 ≦ 0.075 dB may be satisfied when α1 = 0.175 dB.

  Thus, if the transmission loss α1 of the leaky coaxial cable 1 and the transmission loss α2 of the low-loss coaxial cable 4 from the detour output point of the second directional coupler 5 to the power combiner 7 are designed, the radio base station The radio base station apparatus 31 can normally receive radio waves from the radio terminal apparatus in a place where the radio waves from the apparatus 31 can be normally received.

(Fourth embodiment)
This embodiment also describes a radio communication system using a radio base station antenna. The radio base station antenna in this embodiment also has the same configuration as that of the first embodiment described above.

  As shown in FIG. 4, a radio base station apparatus 41 provided with a transmission / reception antenna terminal 41a having a common transmission antenna terminal and reception antenna terminal is used as the radio base station apparatus. The transmission / reception antenna terminal 41 a of the radio base station apparatus 41 is connected to the circulator 42.

  The circulator 42 is connected to the transmission input terminal IN of the radio base station antenna 30 via the coaxial cable 32 and to the reception output terminal OUT of the radio base station antenna 30 via the coaxial cable 33.

In such a configuration, the transmission power from the radio base station apparatus 41 is input to the transmission input terminal IN of the radio base station antenna 30 via the circulator 42 and the coaxial cable 32, transmitted through the leaky coaxial cable 1, and externally transmitted. To be emitted. The received power output from the power combiner 7 to the reception output terminal OUT is received by the radio base station apparatus 41 via the coaxial cable 33 and the circulator 42.
Therefore, also in this embodiment, the function performed by the radio base station antenna 30 is the same as that of the third embodiment described above. Therefore, this embodiment can obtain the same operation and effect as the third embodiment described above.

  In each of the embodiments described above, a leaky coaxial cable is used as the leaky transmission line, but it is needless to say that the present invention is not limited to this. Further, although a low-loss coaxial cable is used as the low-loss transmission line, the present invention is not limited to this.

The figure which shows the structure of the radio base station antenna which concerns on the 1st Embodiment of this invention. The figure which shows the structure of the radio base station antenna which concerns on the 2nd Embodiment of this invention. The figure which shows the structure of the radio | wireless communications system using the radio base station antenna which concerns on the 3rd Embodiment of this invention. The figure which shows the structure of the radio | wireless communications system using the radio base station antenna which concerns on the 4th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11 ... Leaky coaxial cable (leakage transmission path), 3,13 ... 1st directional coupler, 4,14 ... Low loss coaxial cable (low loss transmission path), 5,15 ... 2nd directional coupling 16, third directional coupler, 7, 18, 21, power combiner.

Claims (4)

A leaky transmission line that transmits transmission power from the transmission input end toward the termination unit and transmits reception power toward the transmission input end;
A low-loss transmission line having a transmission loss per unit length smaller than the leaky transmission line;
A first directivity that is disposed near the transmission input end of the leaky transmission path and has a function of passing transmission power from the transmission input end toward the terminator and a function of outputting reception power toward the transmission input end to the outside. A coupler;
A second function that is arranged in the middle of the leaky transmission line and has a function of passing transmission power from the transmission input end toward the terminator and a function of detouring reception power toward the transmission input end to the low loss transmission line; A directional coupler;
Arranged corresponding to the first directional coupler, the received power output from the first directional coupler and the received power from the low-loss transmission line are input, and the combined power is input to the reception output terminal. A radio base station antenna comprising an output power combiner.   The transmission loss of the leaky transmission line between the first directional coupler and the second directional coupler is α1 (dB), which is low from the detour output point of the second directional coupler to the power combiner. When the transmission loss of the lossy transmission path is α2 (dB), the transmission power from the transmission input terminal is P1 (dBm), and the transmission power from the outside received by the leaky transmission path is P2 (dBm), α1−α2 ≧ 2. The radio base station antenna according to claim 1, wherein the first and second directional couplers and a power combiner are arranged so as to satisfy the relationship P1-P2. A leaky transmission line that transmits transmission power from the transmission input end toward the termination unit and transmits reception power toward the transmission input end;
A low-loss transmission line having a transmission loss per unit length smaller than the leaky transmission line;
A first directivity that is disposed near the transmission input end of the leaky transmission path and has a function of passing transmission power from the transmission input end toward the terminator and a function of outputting reception power toward the transmission input end to the outside. A coupler;
A function that is arranged closest to the terminator in the middle of the leaky transmission line, and that allows transmission power to pass from the transmission input end toward the terminator, and a function that bypasses the reception power directed toward the transmission input end to the low loss transmission line. A second directional coupler having
A function of transmitting transmission power from the transmission input end toward the terminator and reception in the direction of the transmission input end disposed between the first directional coupler and the second directional coupler in the leaky transmission path One or more third directional couplers for outputting power out of the leaky transmission line;
Arranged corresponding to the first directional coupler, the received power output from the first directional coupler and the received power from the low-loss transmission line are input, and the combined power is input to the reception output terminal. A first power combiner for outputting;
In the middle of the low-loss transmission line, it is arranged corresponding to the third directional coupler, and the received power output from the corresponding third directional coupler is low on the second directional coupler side. A radio base station antenna comprising a second power combiner that inputs received power from a lossy transmission path and outputs the combined power to a low-loss transmission path on the reception output end side. The radio base station antenna according to any one of claims 1 to 3,
A radio base station device that is connected to this radio base station antenna, transmits transmission power to the transmission input end of the leaky transmission path, and receives reception power from the reception output end;
A wireless communication system, comprising: a wireless terminal device that transmits and receives wirelessly to and from the leaky transmission path and has a transmission power smaller than that of the wireless base station device.

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